Hello @TechLord thank you very much for the quick reply 
The Skeletal Mesh isn’t entirely blank, I have a single poly plane at its root to skin the bones to, to prevent the need to ‘hide’ it, which can also cause problems. I did manage, after a whole lot of google searching, to find a buried solution, whether its ideal or not, I am unsure.
Apparently changing the Parent Mesh (Master Bone Component) from “Always Tick Pose” to “Always Tick Pose and Refresh Bones” solves the issue. The character properly animates in game. However, as I said, I am entirely unsure if this is the ideal solution or not, because any tutorial or post I’ve seen about the Master Pose Component never mentions having to switch this Flag.